From f125fb0afc2e00612701f825c8456acdcb53e55b Mon Sep 17 00:00:00 2001 From: Adrian Holovaty Date: Sat, 19 Nov 2005 18:20:30 +0000 Subject: [PATCH] Beefed up docs/url_dispatch.txt git-svn-id: http://code.djangoproject.com/svn/django/trunk@1291 bcc190cf-cafb-0310-a4f2-bffc1f526a37 --- docs/overview.txt | 12 +- docs/tutorial03.txt | 14 ++- docs/url_dispatch.txt | 271 +++++++++++++++++++++++++++++++++++++----- 3 files changed, 255 insertions(+), 42 deletions(-) diff --git a/docs/overview.txt b/docs/overview.txt index 1f251efcb6..11fa7d1fa9 100644 --- a/docs/overview.txt +++ b/docs/overview.txt @@ -162,9 +162,9 @@ Reporter/Article example, here's what that might look like:: from django.conf.urls.defaults import * urlpatterns = patterns('', - (r'^/articles/(?P\d{4})/$', 'myproject.news.views.articles.year_archive'), - (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'myproject.news.views.articles.month_archive'), - (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'myproject.news.views.articles.article_detail'), + (r'^/articles/(?P\d{4})/$', 'myproject.news.views.year_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'myproject.news.views.month_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'myproject.news.views.article_detail'), ) The code above maps URLs, as regular expressions, to the location of Python @@ -181,7 +181,7 @@ dictionaries -- and the values captured in the regex, via keyword arguments. For example, if a user requested the URL "/articles/2005/05/39323/", Django -would call the function ``myproject.news.views.articles.article_detail(request, +would call the function ``myproject.news.views.article_detail(request, year='2005', month='05', article_id='39323')``. Write your views @@ -280,8 +280,8 @@ This has been only a quick overview of Django's functionality. Some more useful features: * A caching framework that integrates with memcached or other backends. - * An RSS framework that makes creating RSS feeds as easy as writing a - small Python class. + * A syndication framework that makes creating RSS and Atom feeds as easy as + writing a small Python class. * More sexy automatically-generated admin features -- this overview barely scratched the surface. diff --git a/docs/tutorial03.txt b/docs/tutorial03.txt index ebf1515aa3..ad13c323d9 100644 --- a/docs/tutorial03.txt +++ b/docs/tutorial03.txt @@ -60,6 +60,7 @@ regular expression as keyword arguments, and, optionally, arbitrary keyword arguments from the dictionary (an optional third item in the tuple). For more on ``HTTPRequest`` objects, see the `request and response documentation`_. +For more details on URLconfs, see the `URLconf documentation`_. When you ran ``django-admin.py startproject myproject`` at the beginning of Tutorial 1, it created a default URLconf in ``myproject/urls.py``. It also @@ -67,8 +68,7 @@ automatically set your ``ROOT_URLCONF`` setting to point at that file:: ROOT_URLCONF = 'myproject.urls' -Time for an example. Edit ``myproject/urls.py`` so it looks like -this:: +Time for an example. Edit ``myproject/urls.py`` so it looks like this:: from django.conf.urls.defaults import * @@ -88,9 +88,9 @@ associated Python package/module: ``myproject.apps.polls.views.detail``. That corresponds to the function ``detail()`` in ``myproject/apps/polls/views.py``. Finally, it calls that ``detail()`` function like so:: - detail(request=, poll_id=23) + detail(request=, poll_id='23') -The ``poll_id=23`` part comes from ``(?P\d+)``. Using +The ``poll_id='23'`` part comes from ``(?P\d+)``. Using ``(?Ppattern)`` "captures" the text matched by ``pattern`` and sends it as a keyword argument to the view function. @@ -103,6 +103,11 @@ something like this:: But, don't do that. It's silly. +Note that these regular expressions do not search GET and POST parameters, or +the domain name. For example, in a request to ``http://www.example.com/myapp/``, +the URLconf will look for ``/myapp/``. In a request to +``http://www.example.com/myapp/?page=3``, the URLconf will look for ``/myapp/``. + If you need help with regular expressions, see `Wikipedia's entry`_ and the `Python documentation`_. Also, the O'Reilly book "Mastering Regular Expressions" by Jeffrey Friedl is fantastic. @@ -113,6 +118,7 @@ time the URLconf module is loaded. They're super fast. .. _Wikipedia's entry: http://en.wikipedia.org/wiki/Regular_expression .. _Python documentation: http://www.python.org/doc/current/lib/module-re.html .. _request and response documentation: http://www.djangoproject.com/documentation/request_response/ +.. _URLconf documentation: http://www.djangoproject.com/documentation/url_dispatch/ Write your first view ===================== diff --git a/docs/url_dispatch.txt b/docs/url_dispatch.txt index 363d31174a..d08ba702f6 100644 --- a/docs/url_dispatch.txt +++ b/docs/url_dispatch.txt @@ -2,52 +2,244 @@ URL dispatcher ============== -We're fanatics about good URLs. No ".php" or ".cgi", and certainly not any of -that "0,2097,1-1-1928,00" nonsense. Django's URL dispatcher lets you design -your URLs to be as pretty as the rest of your application. +A clean, elegant URL scheme is an important detail in a high-quality Web +application. Django lets you design URLs however you want, with no framework +limitations. -See `the Django overview`_ for a quick introduction to URL configurations; this -document will continue from there. +There's no ``.php`` or ``.cgi`` required, and certainly none of that +``0,2097,1-1-1928,00`` nonsense. -.. _`the Django overview`: http://www.djangoproject.com/documentation/overview/#design-your-urls +See `Cool URIs don't change`_, by World Wide Web creator Tim Berners-Lee, for +excellent arguments on why URLs should be clean and usable. -The view prefix -=============== +.. _http://www.w3.org/Provider/Style/URI: Cool URIs don't change -Here's the example from that overview:: +Overview +======== + +To design URLs for an app, you create a Python module informally called a +**URLconf** (URL configuration). This module is pure Python code and +is a simple mapping between URL patterns (as simple regular expressions) to +Python callback functions (your views). + +This mapping can be as short or as long as needed. It can reference other +mappings. And, because it's pure Python code, it can be constructed +dynamically. + +How Django processes a request +============================== + +When a user requests a page from your Django-powered site, this is the +algorithm the system follows to determine which Python code to execute: + + 1. The system looks at the ``ROOT_URLCONF`` setting in your + `settings file`_. This should be a string representing the full Python + import path to your URLconf. For example: ``"mydjangoapps.urls"``. + 2. The system loads that Python module and looks for the variable + ``urlpatterns``. This should be a Python list, in the format returned + by the function ``django.conf.urls.defaults.patterns()``. + 3. The system runs through each URL pattern, in order, and stops at the + first one that matches the requested URL. + 4. Once one of the regexes matches, Django imports and calls the given + view, which is a simple Python function. The view gets passed a + `request object`_ and any values captured in the regex as keyword + arguments. + +.. _settings file: http://www.djangoproject.com/documentation/settings/ +.. _request object: http://www.djangoproject.com/documentation/request_response/#httprequest-objects + +Example +======= + +Here's a sample URLconf:: from django.conf.urls.defaults import * urlpatterns = patterns('', - (r'^/articles/(?P\d{4})/$', 'myproject.news.views.articles.year_archive'), - (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'myproject.news.views.articles.month_archive'), - (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'myproject.news.views.articles.article_detail'), + (r'^/articles/2003/$', 'news.views.special_case_2003'), + (r'^/articles/(?P\d{4})/$', 'news.views.year_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'news.views.month_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'news.views.article_detail'), ) -The first argument to ``patterns`` is an empty string in the above example, but -that argument can be useful. The first argument is prepended to all the view -functions in the urlpatterns list, so the above example could be written more -concisely as:: +Notes: - urlpatterns = patterns('myproject.news.views.articles', + * ``from django.conf.urls.defaults import *`` makes the ``patterns`` + function available. + + * To capture a value from the URL, use the syntax ``(?Ppattern)``, + where ``name`` is the name for that value and ``pattern`` is some pattern + to match. + + * The ``"r"`` in front of each regular expression string is optional but + recommended. It tells Python that a string is "raw" -- that nothing in + the string should be escaped. See `Dive Into Python's explanation`_. + +Examples: + + * A request to ``/articles/2005/03/`` would match the third entry in the + list. Django would call the function + ``news.views.month_archive(request, year='2005', month='03')``. + + * ``/articles/2005/3/`` would not match any URL patterns, because the + third entry in the list requires two digits for the month. + + * ``/articles/2003/`` would match the first pattern in the list, not the + second one, because the patterns are tested in order, and the first one + is the first test to pass. Feel free to exploit the ordering to insert + special cases like this. + + * ``/articles/2003`` would not match any of these patterns, because each + pattern requires that the URL end with a slash. + + * ``/articles/2003/03/3/`` would match the final pattern. Django would call + the function + ``news.views.article_detail(request, year='2003', month='03', day='3')``. + +.. _Dive Into Python's explanation: http://diveintopython.org/regular_expressions/street_addresses.html#re.matching.2.3 + +What the URLconf searches against +================================= + +The URLconf searches against the requested URL, as a normal Python string. This +does not include GET or POST parameters, or the domain name. + +For example, in a request to ``http://www.example.com/myapp/``, the URLconf +will look for ``/myapp/``. + +In a request to ``http://www.example.com/myapp/?page=3``, the URLconf will look +for ``/myapp/``. + +Syntax of the urlpatterns variable +================================== + +``urlpatterns`` should be a Python list, in the format returned by the function +``django.conf.urls.defaults.patterns()``. Always use ``patterns()`` to create +the ``urlpatterns`` variable. + +Convention is to use ``from django.conf.urls.defaults import *`` at the top of +your URLconf. This gives your module access to these objects: + +patterns +-------- + +A function that takes a prefix an arbitrary number of URL patterns and returns +a list of URL patterns in the format Django needs. + +The first argument to ``patterns()`` is a string ``prefix``. See +"The view prefix" below. + +The remaining arguments should be tuples in this format:: + + (regular expression, Python callback function [, optional dictionary]) + +...where ``dictionary_of_extra_arguments`` is optional. (See +"Passing extra options to view functions" below.) + +handler404 +---------- + +A string representing the full Python import path to the view that should be +called if none of the URL patterns match. + +By default, this is ``'django.views.defaults.page_not_found'``. That default +value should suffice. + +handler500 +---------- + +A string representing the full Python import path to the view that should be +called in case of server errors. Server errors happen when you have runtime +errors in view code. + +By default, this is ``'django.views.defaults.server_error'``. That default +value should suffice. + +include +------- + +A function that takes a full Python import path to another URLconf that should +be "included" in this place. See "Including other URLconfs" below. + +Notes on capturing text in URLs +=============================== + +Each captured argument is sent to the view as a plain Python string, regardless +of what sort of match the regular expression makes. For example, in this +URLconf:: + + (r'^/articles/(?P\d{4})/$', 'news.views.year_archive'), + +...the ``year`` argument to ``news.views.year_archive()`` will be a string, not +an integer, even though the ``\d{4}`` will only match integer strings. + +A convenient trick is to specify default parameters for your views' arguments. +Here's an example URLconf and view:: + + # URLconf + urlpatterns = patterns('', + (r'^/blog/$', 'blog.views.page'), + (r'^/blog/page(?P\d+)/$', 'blog.views.page'), + ) + + # View (in blog/views.py) + def page(request, num="1"): + # Output the appropriate page of blog entries, according to num. + +In the above example, both URL patterns point to the same view -- +``blog.views.page`` -- but the first pattern doesn't capture anything from the +URL. If the first pattern matches, the ``page()`` function will use its +default argument for ``num``, ``"1"``. If the second pattern matches, +``page()`` will use whatever ``num`` value was captured by the regex. + +Performance +=========== + +Each regular expression in a ``urlpatterns`` is compiled the first time it's +accessed. This makes the system blazingly fast. + +The view prefix +=============== + +You can specify a common prefix in your ``patterns()`` call, to cut down on +code duplication. + +Here's the example URLconf from the `Django overview`_:: + + from django.conf.urls.defaults import * + + urlpatterns = patterns('', + (r'^/articles/(?P\d{4})/$', 'myproject.news.views.year_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'myproject.news.views.month_archive'), + (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'myproject.news.views.article_detail'), + ) + +In this example, each view has a common prefix -- ``"myproject.news.views"``. +Instead of typing that out for each entry in ``urlpatterns``, you can use the +first argument to the ``patterns()`` function to specify a prefix to apply to +each view function. + +With this in mind, the above example can be written more concisely as:: + + from django.conf.urls.defaults import * + + urlpatterns = patterns('myproject.news.views', (r'^/articles/(?P\d{4})/$', 'year_archive'), (r'^/articles/(?P\d{4})/(?P\d{2})/$', 'month_archive'), (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'article_detail'), ) -.. admonition:: Note - - More precisely, the actual view function used is ``prefix + "." + - function_name``. The trailing "dot" does not need to be put in the prefix. +Note that you don't put a trailing dot (``"."``) in the prefix. Django puts +that in automatically. Including other URLconfs ======================== -You can also "include" other URLconf modules at any point along the path. This -essentially "roots" a set of URLs below other ones. This is most often used -for a site's "base" URLconf; the ``ROOT_URLCONF`` setting points to a urlconf -module that will be used for the entire site. Here's the URLconf for the -`Django website`_ itself. It includes a number of other URLconfs:: +At any point, your ``urlpatterns`` can "include" other URLconf modules. This +essentially "roots" a set of URLs below other ones. + +For example, here's the URLconf for the `Django website`_ itself. It includes a +number of other URLconfs:: from django.conf.urls.defaults import * @@ -70,6 +262,7 @@ URLconfs, so the following example is valid:: urlpatterns = patterns('foo.views' (r'^$', 'blog.index'), (r'^archive/$', 'blog.archive'), + ) In the above example, the captured ``"username"`` variable is passed to the included URLconf, as expected. @@ -79,11 +272,25 @@ included URLconf, as expected. Passing extra options to view functions ======================================= -There are two ways of passing arguments into your view functions: named captures -from the regex (which you've already seen) and the optional third element -in URLconf tuples. This third element can be a dictionary of extra keyword -arguments that will be passed to the view function:: +URLconfs have a hook that lets you pass extra arguments to your view functions, +as a Python dictionary. - urlpatterns = patterns('myproject.news.views.articles', - (r'^/articles/(?P\d{4})/$', 'year_archive', {key: value, key2: value2}), +Any URLconf tuple can have an optional third element, which should be a +dictionary of extra keyword arguments to pass to the view function. + +For example:: + + urlpatterns = patterns('blog.views', + (r'^/blog/(?P\d{4})/$', 'year_archive', {'foo': 'bar'}), ) + +In this example, for a request to ``/blog/2005/``, Django will call the +``blog.views.year_archive()`` view, passing it these keyword arguments:: + + year='2005', foo='bar' + +This technique is used in `generic views`_ and in the `syndication framework`_ +to pass metadata and options to views. + +.. _generic views: http://www.djangoproject.com/documentation/generic_views/ +.. _syndication framework: http://www.djangoproject.com/documentation/syndication/